Para-hydroxy-para&#39;-ethoxy diphenylamine



Patented Dec. 14, 1937 UNITED STATES PATENT OFFICE PABA-HYDROXY-PABA'-ETHOXY DIPHENYLAMINE' George 0. Strouse, Wilmington, Del.,,assignor to E. I. duzflont ade Nemours & :Crnpany,'Wil mington, 'Del., a corporation of Delaware No Drawing. Application July 25, 1936,

Serial'No. 92,605

10 Claims. (01. 260-128) This invention relates to para-hydroxy-para- 210 2l5 C. during two hours and held at that ethoxy diphenylamine and a process for the protemperature for another two hours or until the duction thereof. reaction was complete. The vessel wasprovided In German Patent No. 333,897 a process is dewith a covert-o allowthewater which formed in 5 scribed for the production of indophenol-like the reaction to escape as a vapor and, at the compounds by the condensation of phenol-alkylsame time, minimize the loss ofpara-phenetidine ethers having afree paraposition or containand hydroquinone byvaporization. ing an alkoxy group. These products are said While the charge was being heated at 210- to turn blue in the presence of alkali and to dis- 215 C., a Solution f 730 Darts/0f Water, Darts 10 solve in sodium sulfide solution forming slightly of 100% sodium'hydroxide (as 30% solution) and colored solutions which turn blue on exposure 10 parts of sodium sulfhydrate'l00% (as 35% to air. One of the products is obtainedfrom solution) was prepared in another vessel. As phenetol and nitrosophenol. In Friedlander, soonas the period of heating at 210-215 C. was 13, 350, the following statement is found: In case finished, e molten Charge s transferredto the assumed formulation of the =dyestufi comthe alkaline sulfide solution with good agitation. pound in DRP 333,897 is correct, not only phenols, This mixture was heated to 75 C, and stirred for but also phenol ethers (as with the, .diazo. comone. hour. ,Then the-solution was filtered-to repounds) unite with nitrosophenols to form ethers move any insoluble residue. ,The' residue was of indophenols of the type "washed with 365-parts of-hot ("10 C.) water containing 4 parts of sodiumhydroxide 100% and CHSOGN= =0." 5.5 parts of sodium sulfhydrate 100%. Finally,

-- the residue was washed with about 100 parts of Stelzner, Literatur-Register der Organischen Water The residue was appatently di'(para" Chemie, Volume 5, page 1227, found the com- Phenetyl)'7paralphgnykgetgwmme' pound foxyeeethoxyl-dipheny1amine with The filtrate and f were collected p reference to. German Patent .No. 333,897. It is vesseland. -i at believed, in :view of the invention hereinafter ethpxy dlphervl-ylamme then preglpltatgd described that the. compound obtained in acnfotn the p t adding i cordance with German Patent No. 333,897 is not unis-11 hqqld Wasneutrm to mymolpht-halmn 30 pam hydroxy para, ethoxy diphenylamine and test paper and alkalineto.phenolphthalein. .In 3

that Friedlander and Stelzner have made incorz p f diphenyl' rest assumptions. amine wasrplecipitated n whatv appeared to be It is an object of this invention to produce a amorphogs -t Phanged quickly para-hydroXy-para'-ethoxy diphenylamine. A mto y i m q i the further object is the provision of a new andimls F- to Impurity proved process for producing said compound. 9311mm fi the .paralhydmxy'paraf'ethoxy Other objectswill appear hereinafter. dlphenylamlp? h d In accomplishing these objects in accordance preempted -W 5 5 with the invention, para-hydroxy-paraQethoxy dl-phenylamm? was filtelved ofi f mih i w diphenylamine has been preparedby the conwhich was Still alkahne to phenqlphthalfim' It densation of paraephenetidine and hydroquinone was washed i l zin the presence of a catalyst suchas zinc chloparts of ,Sodmm t m parts 9 ride. water until the washings were no longer. alkal ne The invention will be further illustrated but t0 Brllhant Yellow test P T-hen w is not limited as to proportions, temperature, washed wlilkw f Water -?.m h b sulfi v etc by the following example in which the quan- It may be fined m a a r m Ye at T tities are stated in parts by weight. dry m e i prepared i 1. Wa m l e about .8334 C. The purpose of washing the Example press-cake with bisulfite solutionis toprevent 50 One hundred (100) parts of para-phenetidine oxidation ofthe par hydro gy-para ethoxy diwere put into a suitable vessel equipped with an phenylami ne when exposed to air. agitator. The agitator was startedand the para- Para hydroxy para ethoxy diphenylamine phenetidine was heated to 100 C. Then parts may be recrystallized iromfhot water. On coolof hydroquinone were added, followed by 3 parts ing, snow-.white crystals are formed. After dryof zinc chloride. This mixture was heated to in'gin avacuum desiccator over suliu'ricacid these crystals melt at 85.5-86 C. When exposed to air they slowly become gray with a reddish-brown tint. Para-hydroxy-para-ethoxy diphenylamine dissolves in dilute sodium hydroxide solution, forming a nearly colorless solution which oxidizes to a red or reddish-brown color on exposure to air. Its alkaline sulfide solutions also oxidize to red or reddish-brown.

While the invention is not limited to any theory, para-phenetidine and hydroquinone apparently react according to the following equation:

para-phenetidine hydroquinone oimoOnnOon Hi para-hydroxy-para-ethoxy water diphenylamine The alkali-insoluble by-product appears to be formed by side reactions of two molecules of paraphenetidine on one molecule of hydroquinone or by the action of one molecule of para-phenetidine and one molecule of para-hydroxy-paraethoxy diphenylamine, as illustrated by Equations (2) and (3), respectively:

The reaction vessel may be suitably made of glass, enamel, stainless steel, nickel or Monel metal. Iron vessels appear to be unsuitable for the reaction.

Para hydroxy para ethoxy diphenylamine produced in accordance with the invention is a useful dye intermediate; for example, bysulfurization it may be converted to a sulfur color. It

may also be used as a gum inhibitor in gasoline or as a means of preventing deterioration of rubber. In itsoxidized form, that is, as para-ethoxyphenyl-imino-quinone, it may be used as a gasoline dye.

It will be apparent from the description given above that para-hydroxy-para'-ethoxy diphenylamine does not have the properties attributed to the indophenol-like compounds of German Patent No. 333,897. It is not blue in the presence of alkali and its sulfide solutions do not oxidize to a blue color. On the contrary, it dissolves in dilute sodium hydroxide solution forming a nearly colorless solution and its sulfide solutions oxidize to red or reddish-brown colors instead of blue. So far as is known, therefore, this compound has not heretofore been described in the art and is a new and useful material.

As many apparently widely different embodipara-phenetidine hydroquinone di- (para-phenetyl) -para-phenylene diamine a amoO-nnO-onnmv-O-oom.

para-h droxyara'-ethoxy pheny amine para-phenetidine The time and temperature of the reaction can be varied through a wide range. Temperatures from 180 C. to 230 C. have been used, and it is probable that both higher and lower temperatures than these could be used. At a low temperature a longer time is required and at a high temperature a shorter time.

Other acid condensing agents, as, for example, ferric chloride, hydrochloric acid and aluminum chloride, may be used instead of zinc chloride. The proportion of the condensing agent may vary but, generally speaking, should preferably correspond to l to 5% by weight of the reaction mixture.

The proportions of para-phenetidine and hydroquinone may be varied somewhat. Ordinarily, it is preferable to use approximately equi-molecular proportions. The invention may be carried out, however, with some advantage by the use of up to excess of para-phenetidine over the theoretical proportions.

The order of addition of the reactants is not considered to be particularly important, although it is more convenient to mix them in such a way that the mixture remains liquid.- For instance, if the hydroquinone and para-phenetidine are mixed cold, the mass will solidify and it is more convenient to mix them in such a. way that the mixture remains liquid. Hence, it is preferable to efiect the mixing with the aid of heat. In making the mixture, the hydroquinone may be added to heated phenetidine, or vice versa.

dipara-phenetyl) -para-pl1enylene diamine ments of this invention may be made without departing from the spirit and scope thereof, it is to be understood that I do not limit myself to the specific embodiments thereof except as set forth in the appended claims.

I claim:

1. Para-hydroxy-para'-ethoxy diphenylamine in the form of white to gray crystals which dissolve in dilute aqueous sodium hydroxide and alkali metal sulfide to produce nearly colorless solutions that oxidize to a red to reddish-brown color, said crystals when purified and dried over sulfuric acid melting at 855 to 86 C.

2. Substantially pure parahydroxy-paraethoxy diphenylamine in the form of snow-white crystals which change to gray with a reddishbrown tint on exposure to air, dissolve in dilute aqueous sodium hydroxide and alkali metal sulfide to produce nearly colorless solutions that oxidize to a red to reddish-brown color, said crystals melting at 85.5 to 86 C.

3. In a process of producing para-hydroxypara-ethoxy diphenylamine, the step which comprises condensing hydroquinone with paraphenetidine in the presence of a small amount of an acid condensationcatalyst under the influence of heat.

4. In a process of producing para-hydroxypara-ethoxy diphenylamine, the step which comprises condensing hydroquinone with paraphenetidine in the presence of a small amount of zinc chloride under the influence of heat.

5. The process of producing para-hydroxypara'-ethoxy diphenylamine which comprises condensing hydroquinone with para-phenetidine in the presence of a small amount of zinc chloride under the influence of heat, mixing the reaction product with an alkali metal sulfide solution, separating any insoluble residue, and precipitating para-hydroxy-para'-ethoxy diphenylamine from the residual liquid by the addition of an acid.

6. The process of producing para-hydroxypara'-ethoxy diphenylamine which comprises condensing hydroquinone with para-phenetidine in the presence of a small amount of zinc chloride under the influence of heat, mixing the reaction product with an alkali metal sulfide solution, separating any insoluble residue, and precipitating para-hydroxy-para'-ethoxy diphenylamine from the residual liquid by the addition of an acid until the liquid is neutral to thymolphthalein paper and alkaline to phenolphthalein.

7. In a process of producing para-hydroxypara'-ethoxy diphenylamine, the step which comprises condensing hydroquinone with paraphenetidine in the presence of a small amount of zinc chloride at a temperature within the range of 180 to 230 C.

8. The process of producing para-hydroxypara-ethoxy diphenylamine which comprises condensing hydroquinone with para-phenetidine in the presence of a small amount of zinc chloride at a temperature within the range of 180 to 230 C., mixing the reaction product with an alkali metal sulfide solution, separating any insoluble residue, and precipitating para-hydroxypara'-ethoxy diphenylamine from the residual liquid by the addition of an acid.

9. The process of producing para-hydroxypara'-ethoxy diphenylamine which comprises condensing hydroquinone with para-phenetidine in the presence of a small amount of zinc chloride at a temperature within the range of 180 to 230 C., mixing the reaction product with an alkali metal sulfide solution, separating any insoluble residue, and precipitating para-hydroxy-para-ethoxy diphenylamine from the residual liquid by the addition of an acid until the liquid is neutral to thymolphthalein paper and alkaline to phenolphthalein.

10. The process of preparing para-hydroxypara'-ethoxy diphenylamine which comprises heating about 100 parts of para-phenetidine to about 100 0., adding about 80 parts of hydroquinone followed by about 3 parts of zinc chloride, then heating the mixture to about 210 to about 215 'C. in about two hours, maintaining said temperature for another two hours while allowing water formed in the reaction to escape, adding the molten reaction product to sodium sulfide solution, heating the mixture to about C. for one hour, separating any insoluble residue, then cooling the residual liquid to about 30 0., adding 30% sulfuric acid. until the liquid is neutral to thymolphthalein test paper but alkaline to phenolphthalein, whereby para-hydroxypara'-ethoxy diphenylamine is precipitated in substantially pure form.

GEORGE C. STROUSE. 

